Vehicle to Grid (V2G) Software Stack (ISO/IEC 15118)

The global consumer electric vehicle market is increasing continuously and impressively. V2G-technology for electric charging communication has become a key technology in this market. V2G is providing standardized Plug & Charge features – automated and secured communication between electric vehicles and charging stations. Tamper-free charging and billing is working fully autonomously.SEVENSTAX V2G is a next level Vehicle-to-Grid communication software stack for embedded systems focusing on an outstanding performance while reducing the memory footprint to a minimum.We help the world’s leading OEMs and suppliers in the automotive and charging equipment fields with innovative software solutions. Reduce your time to market by developing with our worldwide established, ISO 15118 and DIN 70121 conform, SEVENSTAX V2G software stack.

Ensure Your V2G Products Meet ISO/IEC 15118 Standards

As electric vehicle charging evolves, compliance with ISO/IEC 15118 is no longer optional — it’s essential. Regulations such as AFIR (EU) 2023/1804 and the amended Delegated Act for V2G communication are driving the industry to meet communication and interoperability standards. Our advanced Testing Equipment empowers manufacturers and integrators of Electric Vehicles (EV) and Electric Vehicle Supply Equipment (EVSE) to validate conformance with ISO/IEC 15118 and DIN 70121, including support for Plug & Charge. Whether you’re preparing for regulatory certification or ensuring interoperability across networks, our tools provide reliable, automated, and standards-based testing. Get ready for the future of V2G communication — with confidence.

Open Charge Point Protocol

OCPP is an open-source standard protocol for communication between electric vehicle (EV) charging stations and a central management system. It enables interoperability across all charging equipment vendors. Operators can remotely start and stop charging sessions, monitor energy consumption and billing, and view diagnostics in real-time. Our implementation supports the full set of OCPP 2.0.1 messages and includes WebSocket communication, JSON-based data encoding, and TLS encryption for secure connectivity between EV chargers and backend systems. Built with thorough unit testing and validated through code coverage analysis, our OCPP module is ready for seamless integration into charging infrastructures. Fully conformance tested against the official OCTT (OCPP COMPLIANCE TEST TOOL), it ensures stability, performance, and clean integration from day one for public networks or private fleets.

ASPICE-conforming processes and work product quality

In today’s automotive industry, building software is more than writing code; it’s about meeting strict standards for safety, reliability, and maintainability. Frameworks like Automotive SPICE (ASPICE) and coding standards such as MISRA form the foundation of modern automotive software development. As systems grow more complex — from advanced driver assistance to electrification — compliance with these standards is mandatory.We act as your development partner, delivering production-ready software modules that are MISRA-compliant, ASPICE-evaluated, and built on a clean, maintainable architecture. Our approach integrates static code analysis, unit testing, and comprehensive coverage metrics, ensuring every line of code is traceable, testable, and robust.Whether your goal is seamless ASPICE-compliant integration, faster certification readiness, or reduced downstream software risks, our software sets the standard for quality-driven development.

Your Advantages with the Embedded SEVENSTAX V2G Stack

Full Compliance

Exchange standardized XML-based messages (exi compressed) between an Electrical Vehicle (EV) and an Electric Vehicle Supply Equipment (EVSE)
Compliance with ISO/IEC 15118-2 and DIN 70121
AC & DC Charging
External Identification Mean
Plug & Charge
OppCharge Support

Supporting both sides of charging

Charging Stations (Electric Vehicle Supply Equipment)
Electric Vehicles (EV Communication Controller)
V2G Test System
Hardware in the Loop (HIL) test systems

Complete covering all ISO/OSI layers

V2G Application Layer Messages
Embedded TCP/IPv6 Stack
Network Security (TLS 1.2 and 1.3)
SECC Discovery Protocol (SDP)
Wifi drivers (inductive charging)
PLC drivers incl. SLAC (Signal Level Attenuation Characterization)

Easy customer integration

Plain API for fast integration and rapid development
No blocking states, runs with RTOS, OSEK-OS, (Embedded) Linux, Windows and even without OS
Easily accessible predefined V2G message C-structures

Small memory footprint

V2G Library:
ROM: 129 kB
RAM: 14 kB

TCP/IPv6 Stack:
ROM: 64 kB
RAM: 27 kb

Testing Environment:
ARM Cortex M MCU
IAR Embedded Workbench Compiler
Low Optimization

Security

TLS 1.2 and 1.3 (future proof)
ISO 15118-2 & 15118-20 compliant cipher suites
ISO 15118-2 & 15118-20 compliant X.509 v3 certificates
XML Signatures for Plug & Charge

Advantages SEVENSTAX V2G

Written in C (performance)
Optimized for embedded systems
TCP/IPv6 Stack
TLS Stack
Custom user applications
Proven in series production
Meets the quality requirements for automotive area

Fully tested and proven in the field

According to automotive standards
MISRA checked
Automated testing based on SEVENSTAX Test Bench
AUTOSAR Complex Device Driver (CCD) integration

Conformance Tester

Conformance Tester - Test EV and EVSE Communication with Confidence

SEVENSTAX Conformance Tester is a powerful, easy-to-use tool designed to verify the communication compliance of Electric Vehicles (EV) or Electric Vehicle Supply Equipment (EVSE).

With support for the following test standards:

DIN 70122
ISO 15118-4
ISO 15118-5
ISO 15118-21

The SEVENSTAX Conformance Tester features a graphical user interface (GUI) that enables intuitive setup, execution, and evaluation of test scenarios — without requiring deep protocol knowledge. Simply connect your system under test via PLC over the Control Pilot (CP) and start black-box testing. Whether you’re preparing for certification or optimizing your product for interoperability, SEVENSTAX helps accelerate development and ensure compliance with confidence.

V2G Simulator

Simulate EV or EVSE with the SEVENSTAX V2G Simulator

The SEVENSTAX V2G Simulator is a flexible and user-friendly tool designed to emulate either an Electric Vehicle (EV) or an Electric Vehicle Supply Equipment (EVSE) communication for development and testing purposes.

Supporting key standards:

DIN 70121
ISO 15118-2
ISO 15118-20 (upcoming)

This compact device connects directly to the Control Pilot via PLC and is controlled through an intuitive web-based interface — no software installation required. Whether you’re testing interoperability, validating implementations, or simulating charging behavior in the lab, the SEVENSTAX V2G Simulator delivers fast setup, reliable communication, and a smooth Plug & Play experience.

Analyse your communication!

You are developing a Charging Controller or a Charging Station? You need to eavesdrop the communication on the Control Pilot in real time? Then SEVENSTAX GreenShark is your first choice providing you with fully-featured ISO/IEC 15118 protocol analysis. GreenShark is a plug-in for the most powerful Wireshark packet sniffer, which is able to interface SEVENSTAX V2G Win32 Version bringing ISO/IEC 15118 and DIN 70121 support to your PC. This allows EV and EVSE developers to analyse their development results, debug the communication in case of issues and allows reverse engineering of existing implementations.

DIN 70121 EXI Message dissection
SECC Discovery Protocol dissection
V2G Transport Protocol dissection
ISO 15118 EXI Message dissection

Vehicle-to-Grid Background Information

Vehicle to Grid (V2G) is a concept about the intelligent, bidirectional transport of energy between an electric vehicle and the power grid, including a communication standard for electric vehicles describing the communication between charging stations (EVSE – Electric Vehicle Supply Equipment) and vehicles (EV).

The standard is specified by the ISO/IEC 15118 / SAE J2847-2, as well as DIN 70121, which is an early component of the ISO/IEC 15118 and exclusively describes direct current charging.

Currently, the V2G communication takes place via Power-line Communication (PLC) according to the HomePlug Green PHY (HPGP) standard (also compare SAE J2931/4 and ISO15118-3). HPGP could be considered a subset of the prominent HomePlug AV (HPAV), therefore HPAV devices are compatible with HPGP. However HPGP was extended with a few features concerning E-Mobility applications and Smart Metering. Physically, PLC takes place via one of the two electrical lines not used for the charging current of the CCS (Combined Charging System) plug, called the control pilot. However, for this scenario the line coupling of the PLC module must be properly equipped for this task (transmitter, no zero crossover recognition, etc.). Apart from the PLC communication, a rudimentary communication via PWM signal is always taking place on the control pilot. Via the duty cycle it is possible to signal various charging parameters without utilising PLC. If the duty cycle is maintained at 5%, the V2G communication can potentially be initiated (always initiated by the vehicle).

Since as a matter of principle, PLC can include crosstalk of different networks. But it needs to be ensured that the EV is communicating exclusively with the EVSE it is directly connected to. In order to achieve this, Signal Level Attenuation Characterization (SLAC) is used. In brief, when SLAC takes place, the PLC driver of the EV sends a message via broadcast to all PLC devices “nearby”. All EVSE PLC interfaces, that receive this package respond and include the signal strength of the former request into the response as payload. The EV side then chooses the correct EVSE by using the one with the highest signal strength.

After identifying the right EVSE the communication will be initiated by the EV based on IPv6. At the start of the process the IP-address of the EVSE is determined with the use of the SECC Discovery Protocol (SDP) and thereafter the proper TCP based V2G connection is established. Additionally, the connection can be secured utilising Transport Layer Security (TLS).

Two different scenarios for the payment process have been taken into consideration in the V2G communication. When using “External Identification Mean (EIM)” the payment process takes places independently from the charging communication e.g. via credit card at the charging station terminal. Also, the secure transmission of billing information via the communication interface, allows a fully automated payment process: Plug and Charge. As a requirement, the connection has to be secured by TLS. The authentications take place via X.509 certificate and V2G messages are signed. An according certificate infrastructure – Public Key Infrastructure (PKI) is required.

Get in Touch

Contact us to start your V2G kick-off.

We are highly experienced as partner in successful projects with world-leading industry players. We will advise you along the entire development process. We can support you with developing, implementing, as well as testing, providing you with the most fitting solutions, tailored to your project.